Wave energy translator

ABSTRACT

Instrumentation is described for providing indication of the effects of sea conditions on a submerged submarine in a hovering maneuver at a selected depth. The instrumentation comprises analog computational circuitry that operates from the acceleration signal of an automatic hovering system to provide a signal proportional to the degree of difficulty in maintaining an assigned depth.

United States Patent Pietras et al.

[ Oct. 21, 1975 [54] WAVE ENERGY TRANSLATOR 3,769,838 11/1973 Buckler 73/170 A [75] Inventors: Edward F. Pietras, Norwich; Elric J.

Nelson both of Primary ExaminerFelix D. Gruber [73] Assignee: The United States of America as Aflome), 8 firm-Richard SCiaSCia; D,

represented by the Secretary of the Harvey Davld Navy, Washington, DC.

[22] Filed: NOV. 25, 1974 21 Appl. No.: 526,489 [57] ABSTRACT Instrumentation is described for providing indication U-S. Cl R; of the effects of ea conditions on a ubmerged sub- 235/ marine in a hovering maneuver at a selected depth. q (31-2 606G (3066 The instrumentation comprises analog computational Fleld of Search 235/1502, circuitry that operates from the acceleration signal of 73/170, 170 A, 178 R, 183, 503 an automatic hovering system to provide a signal proportional to the degree of difficulty in maintaining an [56] References Cited assigned depth.

UNITED STATES PATENTS 3,610,039 10/1971 Althouse et al 73/189 8 Claims, 2 Drawing Figures loa l2 f ,Is w ,20 a2 24 2s ,2s so ez AUTOMATIC i L novenme SHOOTHING DISPLAY/ SOUA g arl- E I CIRCUIT I RER AVERAGER I INTEGRATOR RECORDER WAVE ENERGY TRANSLATOR STATEMENT OF GOVERNMENT INTEREST The invention described herein may be manufactured and used by or for the Government of the United States of America for Governmental purposes without the payment of any royalties thereon or therefor.

FIELD OF THE INVENTION This invention relates to instrumentation for use primarily during hovering operations of a submarine, and more particularly to apparatus by which a visual and/or recorded indication is provided of the severity of sea state conditions and the effects thereof on the vessels hovering capability.

BACKGROUND OF THE INVENTION There has existed for some time a need for reliable means for quantitatively describing certain environmental conditions prevailing in the immediate vicinity of a submerged submarine. Because of the random nature of many aspects of the sea, and due to the continually changing motions thereof, it is difficult for a submariner to accurately classify and categorize the prevailing conditions by visual inspection. Experience has shown that different conclusions are likely to be drawn by different observers viewing the same conditions through a periscope.

Control of a submarine while hovering, for example,

is heavily influenced by sea state conditions. While surface or near surface water action is regarded as being the prime factor in causing perturbations of a submarine within the influence thereof, wave size, frequency content of surface waves, the heading of the submarine relative to direction or directions of travel of the waves, and operating depth all are significant and interrelated factors affecting the severity of the environment on submarine control. A sea state 3 environment can be severe for submarine control at the periscope depth because of the associated large suction force gradient of that type of sea, and thus be thought to be a state 4 to state 5 sea. However, at a keel depth somewhat greater than that of periscope depth, the severity of this environment would be greatly diminished and would likely be reported as a sea state 1 to 2. The foregoing is indicative of a need for provision of a common denominator in interpreting severity of sea conditions as they relate to submarine operations, so that there can be uniformity within the fleet in the gathering and reduction of patrol data, tactical maneuver considerations and the like.

Inasmuch as hovering under severe conditions increases pump and other machinery noise with increased possibility of enemy detection, and since severe conditions render a submarine more susceptible to loss of control and breaching, it is desirable that a current, visible and dynamic display be available tothe vessel operators.

Moreover, in modern submarines many of the actual trimming adjustments are accomplished automatically by a computer controlled hovering system, therefore the attending personnel do not experience the same sensory or kinesthetic experiences as if the controls were more fully manually effected. Accordingly, there is little actual feel for how hard the system is working to meet a particular environmental situation, or how close it is to not being able to do so.

DISCUSSION OF THE PRIOR ART Various expedients have been employed or proposed for providing a submariner with information on the existing sea state with which the vessel must contend. These have included upwardly directed echo ranging devices as exemplified in U.S. Pat. No. 3,375,715 to F. P. Hodges et al. Such devices are of considerable value in sensing direction of wave travel, and the like, but suffer the disadvantage of not being capable of automatically relating the information to the effects of the surface conditions on the submarine vessel. U.S. Pat. No. 3,098,389 to F. C. Melchoir describes a system for detecting sea surface and barometric conditions. That system likewise does not provide an indication of the severity of sea state effects on the operation of the craft.

Numerous other devices are known for determining wave height and the like, and usually are in the form of a floating buoy comprising accelerometers, clinometers, and telemetry equipment for passing data to a ship or other receiving station. These are, of course not suitable by their character for use by a submarine of the military variety during covert operations.

SUMMARY OF THE INVENTION The present invention aims to overcome most or all of the disadvantages and shortcomings of the prior art through the provision, in a submarine vessel having an automatic hovering or depth control system, of apparatus which translates the effects of surface wave energy on a submarine into a visual display in terms of the severity of such effects.

With the foregoing in mind, it is a principal object of the invention to provide novel and useful instrumentation for use in catagorizing sea surface conditions as they apply to the control of a submarinevessel.

Another object of the invention is the provision of a wave energy translator apparatus that supplants some of the kinesthetic experience of manual control of a submarine vessel with a visual display whereby operators of a vessel having a computer controlled hovering or depth maintaining system are made aware of the degree to which that system is being taxed by the prevailing conditions.

Yet another object of the invention is the provision, in combination with a hovering or depth control system wherein perturbations of the vessel are detected by accelerometer means which provide an acceleration signal that is proportional in amplitude to the sea induced displacing forces and moments as well as to the degree of difficulty of control, of circuitry for deriving from the acceleration signal an energy value signal, and display means for presenting said energy value signal in quantitative terms.

Still another object is the derivation of the energy value signal from the acceleration signal, usually electrical, through the use of operational amplifier techniques to derive a continuously updated energy measurement.

Other objects and many of the attendant advantages will be readily appreciated as the subject invention becomes better understood by reference to the following detailed description, when considered in conjunction with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a representative embodiment of the subject invention.

FIG. 2 is a more detailed circuit diagram of the preferred embodiment of the invention.

In the form of the invention illustrated in FIG. 1, a wave energy translator apparatus is generally indicated at and is 'shown in association with an automatic hovering or depth maintaining control system 12 of the type employed in modern submarines. System 12 senses deviations of the submarine from its assigned depth and automatically produces the necessary changes in ballast and/or other depth controlling elements such as control surfaces, thrusters, and the like. In doing so, system 12 generates an analog signal, usually in the form of an electrical voltage, that is representative of vertical accelerations imposed on the submarine during the hovering manuever. This acceleration signal is depicted by flow line 14.

Apparatus 10 ,is shown in FIG. 1 as comprising a smoothing circuit 16 which receives the acceleration signal 14 from hovering control system 12. The output of smoothing circuit 16 is applied, as shown by line 18, to a squarer 20. Squarer 20 has its output connected via line 22 to an averager 24, which in turn has'its output applied via line 26 to a lagging integrator 28. Integrator 28 has its output'applied, as shown by line 30, to display and/or recorder means 32.

Briefly, the function of apparatus 10 as described in FIG. lis as follows. The smoothed acceleration signal output 18 is squared by squarer 20 and averaged by circuit 24 to provide a mean squared value. The mean squared value is integrated at 28 to provide a signal 30, the magnitude of which corresponds to the rate at which energy is effectively being applied to displacement of the submarine from a specific depth. Display and/or recorder means 32 provides a visual and/or recorded indication of the level of signal 30 against a frame of reference derived from experience so as to give qualitative information value to an observer or reader, all as will be more fully explained hereinafter.

Referring now to FIG. 2, smoothing circuit 16 comprises a conventional operational amplifier 40 which receives the acceleration signal via line 14 and a variable resistor 42. A feedback. circuit is provided comprising a capacitor 44 in parallel with a resistor 46, while the amplifier is referenced above the system or chassis ground via a resistor 48.

Squarer 20 may conveniently comprise a quarter square multiplier 50 with the output of amplifier 40 applied to two input terminals thereof, as shown.

Averager circuit 24, comprises an operational amplifier 54 directly coupled to the output of multiplier 50, and having a feedback circuit comprising a capacitor 56 in parallel with a resistor 58. Amplifier 54 is referenced via resistor 60 to ground.

Integrator 28 comprises an operational amplifier 64 coupled to the output of amplifier 54 via a resistor 66, and is referenced via resistor 68 to ground. A feedback circuit comprises a capacitor 70 in parallel with a resistor 72. The values of the foregoing components, examples of which will be given as this specification proceeds, are selected to produce an output voltage signal, via line 76, resistors 78 and 80, and line 30 to a moving chart type recording meter 82. The latter is conveniently calibrated to reflect the energy conditions of the sea state, as they affect thesubmarine, in terms of Heavy, Moderate, and Light. When used as a recorder, a trace 90 is generated on a moving chart 92 that provides a record, with respect to time, of sea condition effects. This trace is particularly useful in revealing the ability of trim pumps, and the like, in maintaining a predetermined hovering condition. Thus, an upward slope shows increasing difficulty in maintaining hovering depth. A horizontal curve shows that the trim system is meeting hovering requirements, the level of the horizontal curve indicating the degree of difficulty. With little practice, submarine personnel are able to utilize the display in anticipating impending loss of hovering control so as to take timely action necessary to avoid such loss.

The following table gives values of resistors and capacitors as used in an actual working embodiment:

Resistor 42 50K 46 4.7K 48 24K 58 SK 60 5.6K 66 9.1K 68 9.1K 72 l MEG. .80 39K Capacitor 44 .001 MFD. 56 .001 MFD. 390 MFD.

From the foregoing, it will be appreciated that the invention has provided a novel and useful wave energy translator instrument, for submarine use, that achieves the previously stated objects and advantages, as well as others evident from the description of the preferred embodiment.

Obviously, other embodiments and modifications of the subject invention will readily come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoingdescription and the drawing. It is, therefore, to be understood that this invention is not to be limited thereto and that said modifications and embodiments are intended to be included within the scope of the appended claims.

What is claimed is:

l. A wave energy translator apparatus for use in conjunction with a submarine hovering control system providing an acceleration signal which changes in relation to displacement of the submarine from an assigned depth, said apparatus comprising:

smoothing circuit means, connected to receive said acceleration signal, for providing a smoothed acceleration signal; squaring circuit means, connected to receive said smoothed acceleration signal, for providing a squared signal that changes in proportion to the square of said smoothed acceleration signal;

averaging circuit means, connected to receive said squared signal, for providing a mean square signal; and

integrator circuit means, connected to receive said mean square signal, for providing an energy state signal that changes in accordance with the degree of difficulty experienced by said hovering control system in maintaining said assigned depth.

2. Apparatus as defined in claim 1, and further comprising:

indicating means, connected to receive said energy state signal, for providing visual indication of said said indicator means comprises chart recording means.

6. Apparatus as defined in claim 4, and wherein:

said indicator means comprises chart recording means.

7. Apparatus as defined in claim 6, and wherein:

said integrator circuit means comprises a lagging integrator operational amplifier circuit.

8. Apparatus as defined in claim 7, and wherein:

said smoothing circuit means and said averaging circuit means comprise operational amplifier circuits. 

1. A wave energy translator apparatus for use in conjunction with a submarine hovering control system providing an acceleration signal which changes in relation to displacement of the submarine from an assigned depth, said apparatus comprising: smoothing circuit means, connected to receive said acceleration signal, for providing a smoothed acceleration signal; squaring circuit means, connected to receive said smoothed acceleration signal, for providing a squared signal that changes in proportion to the square of said smoothed acceleration signal; averaging circuit means, connected to receive said squared signal, for providing a mean square signal; and integrator circuit means, connected to receive said mean square signal, for providing an energy state signal that changes in accordance with the degree of difficulty experienced by said hovering control system in maintaining said assigned depth.
 2. Apparatus as defined in claim 1, and further comprising: indicating means, connected to receive said energy state signal, for providing visual indication of said degree of difficulty in relative terms of sea conditions with respect to said submarine.
 3. Apparatus as defined in claim 1, and wherein: said smoothing circuit means, said squaring circuit means, said averaging circuit means, and said integrator circuit means all comprise analog voltage circuits.
 4. Apparatus as defined in claim 2, and wherein: said smoothing circuit means, said squaring circuit means, said averaging circuit means, and said integrator circuit means all comprise analog voltage circuits.
 5. Apparatus as defined in claim 2, and wherein: said indicator means comprises chart recording means.
 6. Apparatus as defined in claim 4, and wherein: said indicator means comprises chart recording means.
 7. Apparatus as defined in claim 6, and wherein: said integrator circuit means comprises a lagging integrator operational amplifier circuit.
 8. Apparatus as defined in claim 7, and wherein: said smoothing circuit means and said averaging circuit means comprise operational amplifier circuits. 